Large diameter hole opener for earth boring

ABSTRACT

The present invention is an earth boring device and more particularly a device for expanding a portion of a drilled hole to a greater diameter. The device of the present invention includes a body portion adapted to be attached to the end of, or inserted into, a drill string. A plurality of cutter blades are pivotally mounted upon and circumferentially spaced about the body. Fluid circulation means are provided to supply fluid outwardly along the cutting length of each blade. A mandrel is carried within the body in engagement with a lever arm portion of each blade whereby longitudinal movement of the mandrel pivots each blade from a closed to an opened position. In order to center the drill string in the non-expanded portion of the bore hole, a bearing guide means is provided on the drill string proximate to the expanding apparatus.

United States Patent Leathers Sept. 11, 1973 Clarence H. Leathers, Redondo Beach, Calif.

[73] Assignee: Grant Oil Tool Company, Los

Angeles, Calif.

22 Filed: Dec. 30, 1971 [2]] Appl. No.: 213,956

[75] Inventor:

Primary Examiner-James A. Leppink Att0rneySpensley, Horn & Lubitz [57] ABSTRACT The present invention is an earth boring device and more particularly a device for expanding a portion of a drilled hole to a greater diameter. The device of the present invention includes a body portion adapted to be attached to the end of, or inserted into, a drill string. A plurality of cutter blades are pivotally mounted upon and circumferentially spaced about the body. Fluid circulation means are provided to supply fluid outwardly along the cutting length of each blade. A mandrel is carried within the body in engagement with a lever arm portion of each blade whereby longitudinal movement of the mandrel pivots each blade from a closed to an opened position. In order to center the drill string in the non-expanded portion of the bore hole, a bearingguide means is provided on the drill string proximate to the expanding apparatus.

2 Claims, 14 Drawing Figures PATENTEDSEPI I ma sum 1 or 4 E/z Ami-#52 I N VEN TOR.

LARGE DIAMETER HOLE OPENER FOR EARTH BORING BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates in general to an apparatus adapted to be rotated by an earth drilling string in order to expand a previously drilled hole to a greater diameter upwardly from a point below the earths surface. The present invention is particularly adapted to such hole expansion when the hole is not vertical.

2. Description of the Prior Art The art of drilling bore holes in the earth for a variety of purposes has produced many earth drilling tools. Until recently the drilling of such holes was most generally conducted in connection with oil wells, or the like, and the diameter of such holes was relatively small, being on the order of from eight (8) inches to 22 inches. There has recently been developed the need for drilling holes of greater diameter than heretofore contemplated. The problems encountered in drilling large diameter holes or chambers are different from those previously encountered in earth boring equipment where the holes were of relatively small diameter. Underreamers have been well known for a considerable period of time in the oil well drilling art but such underreamers have normally been utilized to increase the diameter of a hole of, for example, 12 inches to 16 inches. The present invention provides a device for expanding the diameter of a previously drilled hole to form a chamber of large diameter at a predetermined depth belowthe earths surface. For example, in some applications such as drilling platforms positioned above the ocean surface, the platform is supported by support legs which are inclined to the vertical. In accordance with the present invention such support legs can be constructed by forming a foundation support for each leg by drilling and expanding a bore hole for each leg.

In order to do so an underreaming tool is inserted through, for example, a 48 inch casing pipe and expanded to a diameter of many feet. Earth boringtools heretofore known to the art are notcapable of accomplishing this large increase in diameter and particularly so when they must be operated in'a non-vertical condition. I

Accordingly, it is an object of the present invention to provide an apparatus capable of expanding a previouslydrllled hole to form a chamber at a position along the length of the hole substantially below the earths surface, the diameter of the chamber being many times SUMMARY OF THE INVENTION In its presently preferred embodiment the present invention includes a drill string having an underreamer in accordance with the present invention affixed to the lower end of the string. The underreamer comprises a tool body having three cutter blades pivotally mounted thereon movable from a closed position at which they lie adjacent to the body and have a diameter no greater than the casing or bore hole through which the drill string is lowered to an open position at which their cutting diameter is many times the diameter of the bore hole. The blades are pivoted by a pressure operated tubular mandrel within the body. Fluid under pressure is conducted outwardly along the length of the blades and from the blades outwardly through a series of nozzles spaced adjacent the cutting edge of the blades. At least one roller guide means is spaced along the length of the drill string preferably proximate to the underreamer apparatus. Each of the roller guide means includes a non-rotating portion in engagement with the inner surface of the casing of the well bore. The engagement is by means of a plurality of rollers adapted to roll longitudinally within the casing. The rotating portion of the guide means is affixed to the drill string and connected to the non-rotating portion through appropriate bearings such as roller bearings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic of an ocean drilling platform;

FIG. 2 is a view in section of one support leg of the platform with the tool of the present invention in position for underreaming a foundation chamber;

FIG. 3 is a view in elevation of the apparatus of the present invention in closed condition within a well cas- FIG. 4 is a view in elevation similar to FIG. 3 but with the underreamer in the expanded cutting condition;

FIG. 5 is a sectional view taken along line 55 of FIG. 4;

FIG; 6 is a sectional view taken along line 66 of FIG. 4;

' FIG. 7 is an enlarged view partly in section of the underreamer in the closed condition;

FIG. 8 is a partial view in section similar to FIG. 7 showing a single blade in the opened condition;

FIG. 9 is a sectional view taken along ]i ne'99 of FIG. 7; I

FIG. 10 is a sectional view of the guide means of the present invention taken along line l0-10 of FIG. 6;

FIG. 11 is a view in section taken along line lll1 of FIG. 10;

FIG. 12 is a partial view in elevation taken along line 12-12 of FIG. 10; and,

FIG. 13 is a partial view taken alongline 1313 of FIG. 12.

' FIG. 14 is a view in section taken along line 14-14 of FIG. 10.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, there is shown the presently preferred embodiment of the present inven tion.

For purposes of illustration the apparatus of the present invention is shown as utilized for setting foundations for support legs of a drilling platform or similar structure. Although its utility is not limited to this application it is'especially useful for such purpose and accordingly the following description of the presently preferred embodiment is described in that context.

pile driving techniques. As an example, the depth of the sea, shown as A in FIG. 2, above which the platform is positioned may be of the order of 200 feet or more and the structure will be positioned 20 feet or more above the sea surface. In order to obtain structural stability the support legs should be driven to a considerable depth, shown as B in FIG. 2, dependent upon the subterranean earth structure to withstand the severe loadings imposed upon the structure. In the present invention, therefore, the support legs are embedded into the ocean floor to a depth of 200 feet, for example, but set upon large diameter concrete footings to obtain the necessary structural support. Thus, referring to FIG. 2 in accordance with the present invention, the support legs are individually set by driving a tubular casing into the subterranean earth formation or by drilling a hole in such formation and setting a casing by the conventional subsea drilling methods. The casing may itself form the support leg for the platform or a piling member can be set through the tubular casing. Typical diameters employed in the present invention are the utilization of a 48 inch diameter casing which can itself be set upon a concrete foundation or through which a solid 42 inch diameter piling can be set into a concrete foundation. As can be seen by reference to FIGS. 1 and 2, the support legs are inclined to the vertical to obtain increased lateral support. Referring particularly to FIG. 2 there is shown in dotted lines the chamber 23 which is the support chamber into which concrete is to be poured to form a foundation footing for the support leg 21. In the remainder of the FIGURES the opening and casing for the support leg is shown in a vertical orientation for ease of illustration. In FIG. 3 there is shown the tool 30 of the present invention inthe collapsed condition in which it is maintained when being lowered or raised through the hole of unexpanded diameter. In the illustrative embodiment the hole is shown cased by a casing 31 to the depth at which the region of expanded diameter is to be formed. As shown in the drawing the diameter of the casing is of the order of 48 inches and the chamber to be formed .has a diameter of twelve 12) feet. i

The operation of the tool of the present invention in general is such that it is lowered through the previously drilled and cased hole in the retracted configuration as shown in FIG. 3. The tool can be utilized with a drilling bit or without a bit. In the example shown no hit is employed. At the depth where the chamber is to be formed the reaming blades are opened by hydraulic pressure, as described hereinafter, and the reaming to increased diameter occurs upwardly as shown in FIG. 4. That is, the cutting surfaces of the blades are the upper surfaces and cutting to increased diameter takes place as the drill string is raised and rotated. The reaming portion of the tool of the present invention is shown as 30a in the FIGURES and a roller guide portion 30b centers the reaming portion in an inclined hole. Since reaming occurs in an upward direction the guide means is effective throughout the reaming operation. The cutting force of the blades and the load imposed thereon is a function of the upward pull only, which can be carefully regulated without concern for a load imposed by the weight of the drill string as in reaming operations heretofore known to the art.

Referring now to the drawings in detail, the reaming portion 30a of the tool of the present invention includes an elongate tubular body portion 32 adapted to be attached to the lower end of a drill string 33 by means such as a flange 34. The tool body has 11 longitudinal opening 35 therethrough for the passage of circulating fluid through the drill string and for the accommodation of the mandrel 36 as described hereinafter. Three cutter blades 38 are pivotally attached to the tool body and are equally circumferentially spaced about the body in a single transverse plane. At the location at which the cutter arms are pivotally attached to the tool body a pair of spaced apart radially extending plates 39 are attached to the cylindrical portion 40 of the tool body as shown in FIGS. 5 and 9. Thus, there are two plates 39 forming a bracket for each cutter arm and a pivot pin 41 which pivotally mounts the cutter arm between the respective bracket plates. Each of the cutter blade assemblies 38 include a cutter arm portion 43 and a lever arm portion 44, the lever arm portion 44 terminating in a cam 45. The lever arm portion 44 is that part of the cutter blade assembly which extends inwardly from the pivot point 41 through a longitudinal opening 46 in the tool body and terminates at its innermost surface in a cam surface 45. The cutter arm portion is of a length sufficient that when in a fully expanded position, as shown in FIG. 4, the outer most upper edge of the cutter, which point is shown as 47 in the drawings, is of the diameter to which the hole or chamber is to be cut. The entire upper surface 48 of the cutter blade is a cutting edge which is hardened orotherwise formed into a drag cutting edge by means well known to the art. A fluid passage 50 is formed in each cutter arm and extends throughout the length thereof. The fluid bore 50 extends throughout the length of the cutter arm proximate the upper or cutting edge thereof and is in communication with the pivot hole through the cutter arm assembly by which the assembly is mounted upon the pivot pin 41. A series of transverse bores 51 extend from the outer surface of the cutting edge of the cutter arm into fluid communication with the longitudinal fluid bore 50 to form a series of spaced fluid outlets from the bore 50. In the presently preferred embodiment, the outlet bores 51 are formed at about one foot intervals at the edge of the cutter blade. Nozzles 52 may be inserted into the outlet bores 51. Thus, liquid conducted through the longitudinal bore 50 results in a series of jet outlets along the length of the cutting edge of the cutter member. The pivot pin 41 for each cutter blade assembly, is a hollow pin having a fluid opening 53 through the wall thereof, which opening is in fluid communication with the fluid bore 50 of the cutter arm when the cutter arm is in the extended position as shown in FIG. 8. When the blade is in the retracted position as shown in FIG. 9, the liquid bore 50 is out of communication with the opening through the pivot pin such that any fluid conducted to the pivot pin cannot be conducted into the liquid bore 50 and from the jets 51 along the cutter blade. The pivot pins which are tubular have a closed end 55 and an open end 56. To the open end of each respective pivot pin there is connected a fluid conducting pipe 57 which extends from the pivot pin upwardly to an opening 60 in the tool body through which the fluid pipe 57 is in fluid communication with the interior of the upper portion of the tool body above the mandrel piston as described hereinafter. Thus, when liquid under pressure is present in the tool body chamber it will be conducted through the fluid pipe 57 into the pivot pin 41. When the blade is in the extended position, the

opening through the pivot pin wall is in communication with the liquid bore 50 through the cutter blade and from the liquid bore 50 to the series ofjets 51 extended along the cutting edge of the cutter blade.

As can be seen particularly by reference to FIGS. 8 and 9 the cam portion 44 of the cutter blade assembly extends through the longitudinal slot 46 formed through the wall of the tool body and into engagement with a longitudinally moveable mandrel 36 within the tool body.

The cylindrical body portion 40 of the tool body 30 has at the upper end thereof a portion of increased diameter to define by the interior wall thereof the cylindrical chamber 70 which is open at the upper end of the tool body and with which the piston portion of the mandrel described hereinafter is mateable. The cylinder 70 is in fluid communication with the longitudinal passage 81 through the tool body. The mandrel 36 includes an elongate tubular section 82 having an outside diameter less than the diameter of the longitudinal opening through the tool body defined by the interior wall 35. The mandrel terminates at its upper end in a piston section 83 having a circumferential piston flange 85 with an outside diameter approximately equal to but less than the inside-diameter of the cylinder 70. The mandrel is longitudinally moveable within the tool body from a first position as shown in FIG. 7 to a second position as shown in FIG. 8. A'compression spring 86 is positioned between the lower face of the piston flange 85 and a shoulder 87 formed at the lower end of the cylinder 70. An intermediate shoulder 88 forms a stop surface for the piston flange at its lowermost position as shown in FIG. 8. A longitudinal socket 89 terminating at a transverse shoulder 90 is mateable with an inner circulating fluid pipe 91 of the drill string. The fluid opening 92 through the mandrel is in communica tion with the fluid pipe 91. Thus, the piston is in sliding engagement with the pipe 91. Thus, the piston is in sliding engagement with the pipe 91. The piston is urged to its upper position as shown in FIG.'7 by the spring 86 and is moved, to its lower pisition at which the blades are expanded by fluid pressure within the cylinder 70 sufficient to compress the spring and raise the blades outwardly by the cam action of the mandrel with the lever arms of the blades. 1 V

Below the piston head 85 of the mandrel extends the mandrel circulating tube 82 to which the camming flanges 95 are affixed. The mandrel circulating tube 82 is in fluid communication with'the inner drill string tube 91. The camming flanges 95 are fixed to the mandrel and are spaced apart along the length thereof such that one is above the cutter lever arms. Thus, movement of the mandrel downwardly causes the blades to be pivoted outwardly and movement of the mandrel upwardly causes the cutter blades to be retracted.

It is to be noted that in the presentlypreferred embodiment there are two circulation paths through the drill string. Pipe 91 is of substantially lesser outside diameter than the inside diameter of the outer drill string 33. There is thus, a fluid circulating path through the inner pipe and also through the annulus 97 between the inner and outer drill pipes. When a drilling operation is being performed circulation may be reverse or forward using the inner pipe as the circulating pipe. When the cutter blades are to be opened and the underreaming operation commenced circulation is downwardly through the annulus 97 into the pivot pin 41 through the fluid pipe 57 and outwardly through the jets spaced along the cutting edge of each cutter blade. Return circulation is then upwardly through the inner pipe. As the expansion of the blades begins the drill string is raised such that the cutter blades underream the hole upwardly as described hereinbefore as shown in FIG. 4.

Thus, in operation the device of the present invention is lowered through the casing 21 at its minimal overall diameter as shown at FIG. 3 with all of the cutter blade assemblies in the closed position and with the piston and mandrel 36 in the uppermost position as shown in FIG. 7. The tool is lowered on a drill string 33. When the device of the present invention is at a depth at which it is desired to enlarge the hole, circulation of drilling fluid downwardly through the annulus 97 of the drill pipe is commenced. Restriction of the drilling fluid through the fluid pipe 57 from the cylinder causes a large pressure to be exerted upon the piston face and thus, to force the piston 85 and mandrel 36 downwardly. As an illustration of the amount of movement of the mandrel in the described embodiment of the device and to achieve the diameters discussed, the length of travel of the piston and mandrel is approximately 8 inches. When the piston 85 reaches the lowermost limit of its travel as shown in FIG. 8 the cutter blade assemblies are all pivoted outwardly about the pivot points 41 to the configuration as shown in FIG. 4. Continued rotation of the device with upward movement of the drill string causes the hole to be enlarged in the manner previously described and as shown in FIG. 4 at which the cutter blades expand the hole to form a-chamber 144 inches indiameter. In order to remove the apparatus from the expanded hole it is necessary only to discontinue circulation of drilling fluid to thereby discontinue the pressure on the piston face 85. The drill string is then raised and as the cutter arms engage the decreased diameter of the casing in their ascent from the hole they are forced downwardly and force the mandrel upwardly to put the device in a closed configuration as shown in FIGS. 3 and 7.

The platform support legs are then anchored on a concrete foundation by pumping concrete to fill the chamber 23 to either surround the support legs or to provide a support foundation upon which the support leg can be positioned. I

Referring now particularly to FIGS. 10 through 13, the guide means 30b portion of the tool in accordance with the present invention is shown in detail. The bear-- ing guide of the present invention includes a rotating cylindrical body 100 which is affixed to the drill string 33 for rotation therewith. The body 100 can be affixed to the drill string in any manner known to the art as by forming it in two semi-cylindrical sections which are bolted or welded together on the drill string. To assure frictional engagement of the body to the drill string surface a frictional pad 101 of elastomeric or other suitable material is compressed between the body 100 and the outer surface of the drill string 33. A sleeve 102 within which the body 100 is free to rotate is rotatably affixed to the body 100. Thus, the sleeve 102 is a cylinder having an inside diameter greater than the outside diameter of the body 100 and is longitudinally affixed thereto by a series of ball bearings 103 positioned in races 103a in the opposed surfaces of the sleeve and body. A series of roller bearings 104 are also positioned in rolling engagement between the surfaces. Suitable seals 1040 are provided to protect the ball and roller bearings.

On the exterior surface of the sleeve 102 there are affixed three circumferentially spaced roller guide assemblies 105 all of which are of the same construction. The roller guides 105 include three rollers 106 which are in longitudinally rolling engagement with the inside surface of the hole as defined in the illustrative embodiment by the casing 31. Each of the roller guide assemblies includes a mounting block 107 which is welded to or otherwise affixed to the sleeve 102. The mounting block defines a recess in which a radially moveable bearing block 108 is mounted. Thus, as shown particularly in FIGS. 10 through 13, the mounting block defines an outwardly facing recess 110'into which the bearing block 108, which is of lesser thickness than the depth of the recess is fitted. Removeable plates 110 are bolted to the mounting block after the bearing block is inserted to retain the bearing block by means of engaging shoulders 111. A plurality of cavities 112 are formed in the inner surface of the block and compression springs 114 are inserted into the cavities. The springs 114 urge the bearing block radially outwardly from the recess. A roller 106 is rotatably mounted in the bearing block upon a shaft 117 which is mounted transversely to the drill string axis for rotation of the roller 106 in the longitudinal direction of the drill string and easing wall.

In operation as the drill string and underreamer assembly of the present invention are moved downwardly through the hole which is cased in the illustrative embodiment the rollers 106 are urged into engagement with the inner wall of the casing 31 to maintain the drill string centered within the casing. While the guide assembly 30b is moving longitudinally within the casing the springs 118 force the bearing block 108 carrying roller 106 outwardly. The roller is free to roll longitudinally along the inner surface of the casing but is not rotating with respect to the casing. The drill string 33 and What is claimed is:

1. A well bore expanding tool adapted to be inserted into a well bore for an expansion of a portion of the bore beneath the earths surface comprising:

an elongate tool body adapted to be affixed to a rotary drill string;

a plurality of cutter blades pivotally mounted upon said body, said blades being circumferentially spaced about said body and in transverse alignment;

a mandrel longitudinally movable within said body;

means for moving said mandrel downwardly in response to fluid pressure in said drill string;

means interconnecting said mandrel and said blades whereby said blades are pivoted outwardly and upwardly to an opened cutting position in response to downward movement of said mandrel;

cutting edges along the upper surface of each of said blades adapted to expand the well bore as said drill string is raised and rotated with said blades expanded;

a fluid conducting bore extending longitudinally through each of said cutter blades, a series of fluid outlets spaced longitudinally along the length of said blade in communication with said bore;

a fluid conducting conduit extending through said tool body to a fluid outlet proximate each of the pivot points for said blades; and

said fluid conduit and said fluid bore being so constructed that they are in fluid communication at the open position of said blade whereby fluid is conducted outwardly from said blade toward the surface of the well bore being cut when said blades are in the cutting position.

2. The apparatus as defined in claim 1 wherein each of said cutter blades includes a lever arm portion extending inwardly of said tool body past said pivot points;

each said lever arm portion terminating in a cam surface engageable with a camming surface on said mandrel. 

1. A well bore expanding tool adapted to be inserted into a well bore for an expansion of a portion of the bore beneath the earth''s surface comprising: an elongate tool body adapted to be affixed to a rotary drill string; a plurality of cutter blades pivotally mounted upon said body, said blades being circumferentially spaced about said body and in transverse alignment; a mandrel longitudinally movable within said body; means for moving said mandrel downwardly in response to fluid pressure in said drill string; means interconnecting said mandrel and said blades whereby said blades are pivoted outwardly and upwardly to an opened cutting position in response to downward movement of said mandrel; cutting edges along the upper surface of each of said blades adapted to expand the well bore as said drill string is raised and rotated with said blades expanded; a fluid conducting bore extending longitudinally through each of said cutter blades, a series of fluid outlets spaced longitudinally along the length of said blade in communication with said bore; a fluid conducting conduit extending through said tool body to a fluid outlet proximate each of the pivot points for said blades; and said fluid conduit and said fluid bore being so constructed that they are in fluid communication at the open position of said blade whereby fluid is conducted outwardly from said blade toward the surface of the well bore being cut when said blades are in the cutting position.
 2. The apparatus as defined in claim 1 wherein each of said cutter blades includes a lever arm portion extending inwardly of said tool body past said pivot points; each said lever arm portion terminating in a cam surface engageable with a camming surface on said mandrel. 